1. Field of the Invention
The present invention relates to the liquid crystal display field, and particularly to a liquid crystal display device, a four-color converter, and a conversion method for converting a RGB data to a RGBW data.
2. Description of Related Art
Currently, in a display device having a liquid crystal display panel (LCD) or an organic light emitting diode display panel (OLED), a pixel is formed by a red (R) subpixel, a green (G) subpixel, and a blue (B) subpixel. Through controlling the grayscale value of each subpixel, a color required to be displayed is mixed. With the development of the information technology, various requirements for the display panel are increased. High light transmittance, low power consumption, good image quality has become a people's demand for the display panel. The light transmittance and mixing efficiency of the current RGB color mixing method are lower such that the power consumption of the display panel is large so as to limit product optimization of the display panel. Therefore, a technology that a pixel is formed by a red (R) subpixel, a green (G) subpixel, a blue (B) subpixel, and a fourth subpixel is generated to improve the display quality of the RGB display panel.
More commonly, the increased fourth subpixel is a white (W) subpixel, that is, a pixel is formed by a red (R) subpixel, a green (G) subpixel, a blue (B) subpixel, and a white (W) subpixel. The display device having a RGBW display panel require converting an original RGB date to a RGBW data required to be displayed in order to drive the RGBW display panel and displaying. However, the current method used to convert the original RGB date to the RGBW data usually has to satisfy a relationship: W=R+G+B.
FIG. 1 is a light transmittance spectrum diagram of a W subpixel according to the conventional art. FIG. 2 is a light transmittance spectrum diagram of an R subpixel, a G subpixel, and a B subpixel according to the conventional art. With reference to the FIG. 1 and FIG. 2, in the actual situation, the backlight (such as a blue light) generated by the backlight module is directly emitted from the W subpixel (usually formed by a transparent photoresist). The relationship of W=R+G+B for each subpixel is difficult to meet. Furthermore, the light emitted from the W subpixel is highly similar with the light emitted from the B subpixel. Because the combined effect of the light emitted from the W subpixel and the light emitted from the B subpixel, the white color spectrum displayed by the RGBW display panel cannot be located in a normal range such that the chromaticity displayed by the RGBW display panel is abnormal.